Cargill - Transform the grid

Grid reliability is a key issue that is directly influenced by transformer design and operation - Cargill's Envirotemp FR3 natural ester fluid can help break current transformer paradigms to truly improve it.

An electrical grid's reliability is directly affected by transformer design, loading, maintenance policy and ambient conditions. Furthermore, new grid conditions, including distributed generation, may create additional disturbances for the interconnection element: the transformers.

To truly improve grid reliability not only takes a good solution but also requires some changes to how the industry usually approaches transformer management.

Based upon the historical capacity of transformers deployed for a given demand, utilities preordained the aging rate of their transformer fleet and hence the reliability of the grid. As a more complex grid has emerged, variable loading patterns have increased and, as a result, new dielectric stress is accelerating the aging rate of the transformer fleet, threatening the long-term reliability of the grid.

Slowing the aging rate of transformers is paramount. Utilities balance many variables when deciding which transformers to deploy to a particular circuit. Some decisions are based solely on utility practice, such as supplying transformers from standardised inventories. While standardisation is a good best practice, supplying oversized mineral-oil-filled transformers that are unnecessarily under-loaded inflates initial and total ownership costs. Cargill supports the benefits of standardised inventories but suggests looking at which capacities are standardised and why.

A simple solution is to change the dielectric fluid and improve transformer designs. By incorporating Envirotemp™ FR3™ natural ester fluid into their transformer specifications, utilities can realise significant cost savings, increase transformer fleet performance and improve grid reliability. Here's how:

1. Protect the insulation paper from premature aging and dielectric failure

FR3 fluid should delay dielectric failure in most transformers, as the insulating paper stays stronger for longer, even at elevated operating temperatures of up to 20°C. Installing transformers filled with FR3 fluid will improve a transformer's life expectancy by extending the life of its insulating materials. This means improving transformer reliability and, in the long run, a utility's grid reliability.

2. Change transformer design with FR3 fluid to handle load variability without sacrificing reliability or asset life

Today, several standards exist that define maximum operating temperatures for insulation systems composed of typical insulation components, all focused on long-term life expectancy. As now standardised, transformer insulation systems with FR3 fluid can be designed with a 20°C increase in temperature and still meet the standard aging rate. By specifying transformers optimised to the new standardised high-temperature capabilities, utilities could: specify smaller transformers than traditional mineral-oil-filled transformers based on incremental temperature increases up to 20°C; or specify similar-sized transformers but allow the operational temperature to increase 10-20°C in order to provide more flexibility in managing demand peaks. In either case, these FR3-fluid-filled transformers would:

  • meet changing capacity requirements
  • achieve a slower insulation-aging rate, resulting in
  • longer-lasting solid insulation
  • have lower no-load losses than a mineral-oil transformer
  • mitigate the risk of fires - FR3 fluid has a 360°C fire point
  • reduce the amount of resources used, such as copper, electrical grade steel, paper, fluid and so on
  • potentially realise first-cost savings or reduce total cost of ownership.

Reliability advantages are achievable today

Transformer manufacturers are designing FR3 fluid-filled transformers that operate within the temperature limitations outlined in IEEE/IEC and other international standards while providing access to the thermal capabilities. Utilities are improving performance by adopting FR3 fluid and changing their usage profiles.

By resizing their transformers, requesting new configurations - including multiple capacities, such as 65/75/85C AWR ratings - and changing how those assets are applied, the transformer industry could reshape the electric grid into a more reliable distribution system.

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See IEC 60076-14 and IEEE C57.154 standard for design...
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